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    <title>Document</title>
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<body>
    <button id="ldh">刘德华</button>
    <button id="zxy">张学友</button>
    <img src="images/ldh.jpg" alt="">

    <script>
        var ldh = document.getElementById('ldh');
        var zxy = document.getElementById('zxy');
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        zxy.onclick = function () {
            img.src = 'images/zxy.jpg';

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            img.src = 'images/ldh.jpg';
        }
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